This invention is generally directed to a machine and method for forming inside corners in a one-piece panel or other one-piece article, and more particularly for forming grooves or members defining profiles that merge or meet at corners to define miter lines, such that the corners have inside corner portions. The invention is particularly useful in producing one-piece raised panels.
Raised relief panel construction is widely used such as for cabinet and full-length wall doors. Typically, such construction is with multiple pieces including stiles, rails, and central panels, machined and joined together to form the raised panel door. Such a construction has found great customer appeal and acceptance. Nevertheless, this old type construction is relatively expensive considering the labor costs involved, and has proven to be completely unsatisfactory for certain types of cabinet and door finishes.
For example, certain new high gloss, paint, veneer, and laminate finishes have become popular. They require a core that is dimensionally stable to resist cracking. Because the old stile and rail construction expands and contracts with changes in temperature and humidity, it is not suitable with many of these finishes as cracks will develop in the finish and become unappealing.
One attempt to solve the problem of cracking, at least with respect to a high gloss finish, has been a product having an outer plastic layer molded on a wood core. However, the product is relatively expensive, and because it is produced by molding only certain sizes are available thus limiting the availability of the product for certain customer applications.
The present invention provides a solution. In accordance with the machine and method of the present invention, and with particular reference to raised panels, a one-piece raised panel can be produced easily and inexpensively.
It is formed from a single board or workpiece having length and width dimensions of that of the panel to be formed. Grooves are formed in a face surface of the work piece with the cross-section of the grooves being of a selected shape. Preferably, the grooves are of constant and identical cross-section. The grooves surround a central portion that gives the appearance of a raised panel because of the relief or recess formed by the grooves. A raised border area surrounds the grooves and has the same appearance due to the relief provided by the grooves as the stiles and rails of the conventional raised panel construction. The panel is formed from a material that may be readily machined by shearing and may include any suitable wood-like material, such as natural wood, particle, or fiber board (including what is known in the trade as medium density fiber board), as well as plastics, foam, or other synthetics or composite materials.
The problem is with machining the grooves at the corners such that the grooves meet to define miter lines and such that the cross-sectional shape of each groove remains constant all the way into the corner areas. The central portion of each groove can be machined using a routing technique, spindle shaper, or the like, with a rotary cutter that gives the desired cross-sectional shape to the groove. However, such machining techniques cannot be used to form the inside corner portions at the corners.
In accordance with the method of the present invention the central portion of each groove is formed by machining a face surface of the panel using a spindle shaper or similar wood working machine. Preferably such machine is used to form the majority of the groove except for the extreme corner areas and particularly except for the inside corner portions at the corners. Such a machine may not form so much of the corner area of a groove that it cuts into the adjacent groove at the corner.
The machining of the corners is completed by shearing the material at each corner using a shear cutter with a cutting edge that conforms to the cross-sectional shape of the groove. The cutter fits in the groove portion previously formed by the rotary cutter and moves along the groove to complete the machining of the corner area. The cutting edge of the cutter is mitered so that it aligns with the miter line when the cutter is at a corner. After a first shear cutter is moved along one of the grooves into the corner to complete the machining of the one groove at the corner area, a second cutter having a cutting edge that conforms to the shape of the adjacent groove is moved along the adjacent groove into the corner to complete the machining of that groove, and hence the machining of the corner. The results are a perfectly machined grooves that surrounds the raised central panel and which themselves are surrounded by a raised border and where each groove is of constant cross-section even into the extreme corner areas.
In accordance with the machine of the present invention there is provided a table for supporting a panel having the grooves partially formed by a rotating cutter. The machine further comprises first and second cutter assemblies, each having a shear cutter mounted for movement along a path between retracted and extended positions, the path of movement of the cutter of the first assembly merging at a corner with the path of movement of the cutter of the second assembly. The panel is mounted on the table with the cutters positioned and seated within adjacent grooves. Means are provided for driving each of the cutters along its respective path, within the groove in which it is positioned, between the retracted and extended positions. Driving each cutter to its extended position shears the material near the corner to form the remainder of the groove including the inside corner portion at the extreme corner. Adjustments are provided to accurately position the cutters in the grooves.
While the invention is particularly useful in producing one-piece raised panels, it is readily adaptable for producing other one-piece articles having inside corners that may not be formed using rotary cutters. For example, the invention can be used for producing one-piece frames having inside corners.
Hence it is a primary object of this invention to provide a machine and method for forming inside corners in a one-piece panel or other one-piece article that is of high structural quality, inexpensive to manufacture, and possesses the advantages of dimensional stability and crack resistance afforded by one-piece construction.